There are a variety of methods currently in use for providing local anaesthetic in dentistry. These methods and apparatuses however all have disadvantages, either being difficult for practitioners to perform or painful and unpleasant to the patient.
An example of a method used currently in dentistry is the infiltration method, whereby a local anaesthetic solution is injected into the soft tissue of gingiva. In doing so, the solution eventually passes through the cortical plate affecting the nerve bundle entering the tooth. Disadvantages of this method include the delay of onset of anesthesia after the injection and, in most cases, ballooning of the injected tissue. As well, there is an extended period of time for recovery of the tissue until return to normal condition.
Another method which is currently used is the regional block method whereby an anaesthetic solution is injected locally in proximity to the nerve trunk as it enters the bone. Disadvantages of this procedure are that it is extremely difficult to locate the nerve trunk, there is discomfort to the patient and a delay for the anaesthetic to take effect. As in the case of the infiltration method, this method necessitates a long recovery period for tissue to return to normal.
At present, two types of apparatus have been used to perform intra-osseous anaesthesia. These are surgical burs used to perforate the cortical plate and the villet injectors.
The use of a surgical bur has disadvantages in that burs are expensive and they have to be sterilized between uses or a new bur used each time. In addition, the method is slow, requiring the attached gingiva and periosteum to be anaesthetized before the cortical plate is perforated. The villet injector is an apparatus that serves both as a perforator and injector. It uses specially designed needles rotated by a conventional dental motor. A disadvantage of this device is that the needle often becomes clogged with pulverized bone which obstructs the passage in the needle and prevents injection of the anaesthetic solution. It is generally difficult to remove the clogging material from the needle and often the use of a second needle is necessary. Other disadvantages of this method include the initial capital cost of the instrument purchase, and the cost of the needles which are somewhat expensive. In addition, the design of the instrument makes access to various parts of the mouth difficult and sometimes impossible.
Intra-osseous and targeted root-canal nerve anaesthesia have not become popular for the reason that there has not been a practical technique of making the injections successfully. For example, there has been a general belief that this method is radical and to be restored to only if nerve block and infiltration anaesthetic do not accomplish the desired result. However, intra-osseous and targeted injections produce positive, more profound anaesthesia and could be made with less pain than either of the other types according to the present invention.
Targeted anaesthesia has several advantages over prior art nerve block or infiltration methods. There is no feeling of numbness in the tongue, cheek, or lips during or after the injection and there is no after-pain. The anaesthetic is profound and acts immediately alleviating the necessity of waiting for the anaesthetic to take effect as with the nerve block and infiltration methods. Furthermore, as only a few drops of anaesthetic are injected, there is no feeling of faintness or increasing of the pulse rate.
To achieve targeted anaesthesia one must gain access, if intra-osseous, to the cancellous bone by going through the cortical layer; or to the bottom of the tooth, if root-canal targeted anaesthesia is desired. Because of instant anaesthesia and profound pulpal anaesthesia, there is a much greater control over the region one wishes to anaesthetize, resulting in a much smaller dose of anaesthetic; as well as, of course, other medication, where applicable.
U.S. Pat. No. 5,173,050 (Dillon) discloses a dental apparatus for perforating the cortical plate of human maxillary and mandibular bones. The apparatus of Dillon comprises a metal needle moulded into a plastic shank. The shank is being formed with means for cooperation with a dental hand piece for transmitting the rotational movement to the needle. The needle used for drilling is solid and has a sharp bevelled free end. The apparatus described by Dillon is disposable.
However, the device disclosed in Dillon's patent cannot be used as a catheter for injecting anaesthetic by inserting a hypodermic needle through the drilling needle. As well, the device disclosed by Dillon is not provided with means for blocking entry of bone debris into the needle passageway. In addition, the direct connection between the hand piece and the perforator does not provide for a safe and reliable barrier against bacteria passing from the needle to the hand piece.
U.S. Pat. No. 3,534,476 (Winters) discloses a drilling and filling root canal apparatus. The drilling is performed by a drill having a central bore. The depth of the root canal is determined in advance and a stop is placed on the drill to limit the depth of drilling. The device is provided with a flexible rod which is pushed into the root canal so that the drill is directed along this road to follow the contour of the canal so that resulting bore will have an uniform diameter which is free of shoulders or ledges. The apparatus disclosed by Winters is concerned with enlarging the root canal after the nerve has been extracted. This apparatus is not used for injecting medication in close proximity to a targeted area for treatment or anaesthetic.
U.S. Pat. No. 4,944,677 (Alexandre) discloses a smooth hollow needle with a bevelled point for drilling a hole into the jawbone near the apex of the tooth to be anaesthetized. Thereafter, the drilling device 13 removed from the jaw, and a hypodermic needle of substantially the same gauge is inserted into the hole and anaesthesia is injected. Thus, there is no cathetized delivery of medication, with the attendant disadvantage that the pre-drilled hole may be difficult to locate when inserting the hypodermic needle.
One significantly older United States patent that is discussed by Alexandre (above) is U.S. Pat. No. 2,317,648 (Siqveland) granted in 1943. In addition to the disadvantage mentioned by Alexandre, the fact that Siqveland teaches use of threaded sleeve which penetrates the bone during drilling and is left (screwed) in the bone to serve as a guide for insertion of the actual injection needle. Due to the cost of such a device, it cannot be made disposable; but more importantly, for the threaded sleeve to be securely fastened in the bone it would have to rotate at a much slower speed than the drill (as in Siqveland) or the drilling catheter (as in the present invention).
Several other U.S. patents such as U.S. Pat. No. 5,332,398 in the name of Miller, and U.S. Pat. No. 4,969,870 in the name of Kramer have followed the teaching of Siqveland wherein the catheter is at least somewhere along its outer periphery threaded, or designed to implant itself fixedly within the bone it is being disposed in; Furthermore, designs of this type require slowly turning the drilling shaft (or catheter sleeve) into the bone until resistance is encountered at which point the catheter is determined to be in place.
Over the past 50 year or so, and at least since the invention of Siqveland, patented in 1943, devices and processes for intraosseous anesthesia have been developed and refined. However, heretofore, no other inventors have provides a useful, workable convenient and inexpensive solution that affords all of the benefits provided by this invention. For example, non of the prior art devices allow a motorized handpiece to drive a small intraosseous catheter/drill having a rod/drill therein wherein the device can be placed by drilling at high or slower speeds and removed by simple withdrawal by pulling out the catheter. Most of the effort in this field had been directed toward longer term delivery of medication wherein the catheters have had some means of latching into the bone for more permanent placement. Furthermore, the instant invention does not suffer from may of the drawbacks of inserting the needle/drill into the bore being cut by the end tip of the drill, since the outside walls of the needle/drill are of a uniform diameter and non-varying. With the long-felt want of this device, in the past decade in view of the many publications in this field, no such optimal device has been suggested.
In contrast to the prior art, the instant invention provides a dual purpose perforator which includes a needle/sleeve that serves as a relatively high-speed drill bit and which serves as a catheter that is removable by withdrawing it by pulling it out, and not by unscrewing it. The perforator has a substantially uniform outer diameter and has a smooth non-threaded outer surface; preferably, the catheter is a larger gauge needle than the removable rod contained within which may also be in the form of a beveled needle for preventing bone, skin and debris from entering the catheter during entry into the bone. A hypodermic needle of same gauge as the rod is later placed in the catheter after the rod is removed.
Advantageously, the beveled end of the rod assists the cutting of the opening into the bone along with the perforator as they are both rotated by the dental hand piece they are coupled therewith.
To our knowledge, there are no prior art patents, which teach the use of a perforator having a hypodermic needle-like cutting tool wherein the outer diameter is uniform allowing both precise cutting of a small hole, and allowing easy removal by simply pulling the device out without unthreading, wherein the perforator has an upper end adapted to be connected to a motorized dental hand piece; and, wherein the perforator has a rod therein which turns with the perforator needle-like cutting tool assisting in preventing debris from entering the perforator; and wherein the rod is itself a needle-like cutting tool assisting in the cutting of the opening.
To our knowledge, aside from the parent patent application, now issued as U.S. Pat. No. 5,332,398, there are no prior art patents, which teach the use of a perforator having a hypodermic needle-like cutting tool wherein the outer diameter is uniform allowing both precise cutting of a small hole, and allowing easy removal by simply pulling the device out without unthreading, wherein the perforator has an upper end adapted to be connected to a motorized dental hand piece; and, wherein the perforator has a rod therein which turns with the perforator needle-like cutting tool assisting in preventing debris from entering the perforator; and wherein the perforator serves as a catheter for accommodating a hypodermic needle having a same outer diameter as the rod, after the catheter is inserted into the bone.
It is the belief of the inventor, that this novel method and combination of elements will eventually change the way in which many dentists infuse medication and local anesthesia.
Unlike the prior art catheters the catheter drill of the instant invention will not bind or increase its resistance against the drilling hand piece as it is drilling into the bone. The uniform outer diameter allows the drill/needle to cut without binding and acting as a self-tapping hollow screw.